It doesn't get any closer. American Express reassumed the top position in the Power List after two years behind Expedia, which slips to second place. The difference was minimal, with Amex at $29.3 billion in sales and Expedia at $29.2 billion: a virtual dead heat. And close behind, as it has been, in third place is Carlson Wagonlit Travel, at $28 billion.

But the bigger story for 2011 was the strength of the Power List companies and their recovery from the struggles of the previous couple of years. Consider:

• Five companies registered more than $20 billion in sales, including a snowballing Priceline, which showed significant increases each year.

• There were 16 listees with sales of more than $1 billion, up from 14 last year. They included the returning STA Travel, which did not participate in last year's survey.

• There were five more companies on the Power List this year, including a number of new ones. That is a reversal of the trend in recent years, when the list shrunk. One longtime listee, Casto Travel, barely missed the mark this year, with $99 million in sales.

• Many of the listees registered surges in year-over-year sales, a couple by acquisitions but most by generating additional revenue from existing clients or winning new clients. Sales at Priceline jumped more than 50%, to $21.7 billion. Smaller agencies also registered large increases, such as TS24, which moved from $594 million to $724 million.

While the pace of mergers and acquisitions among large companies has slowed, Directravel was purchased by an investment group and subsequently acquired CRT, resulting in a much larger combined company, with sales of $500 million.

When asked what was new or coming up, most mentioned technological advancements -- and, not surprisingly, many of those consisted of apps and other mobile enhancements. The other major trend involved the inexorable move toward globalization: affiliating with companies internationally or opening offices outside the U.S.

Also, a growing number of listees are based outside the U.S. or are subsidiaries of such companies. The Power List requires that 15% of sales come from the U.S. One new listee that is a subsidiary of a company based outside the U.S. is H.I.S. USA, with a Japan-based parent.

Companies with unique niches continued to do well, such as Loyalty Travel, which operates on a membership basis; Global Crew Logistics, most of whose business involves flying aviation crews from location to location; and Quality Reward Travel, all of whose sales are from reward and incentive travel.

Several companies whose sales are all or overwhelmingly leisure-based made the list again, including Expedia, Priceline, FC, AAA, Travelong, Avoya, OneTravel and Global Travel International.

Finally, many companies replied to a "looking ahead" question by projecting sales increases ranging from 10% to 30%. A few projected flat sales, but nobody forecast a downturn. If the trends continue as is, look forward to more billionaires and even stronger sales in next year's list.

The compilation of Power List 2012 began late last year with adjustments to the questionnaire sent to potential listees.

Early this year, the questionnaire was sent to roughly 70 companies that had either appeared on the list in previous years; had been in the news because of acquisitions or had grown for other reasons; or had contacted Travel Weekly believing they qualified (there were more than the average number of these this year).

All questionnaires were sent by email. All were returned by email -- the first time none were returned by fax.

In an effort to keep up with relentless changes, questions were added, removed and tweaked to make them relevant.

As was the case for the last few years, Travel Weekly requested that gross sales volume -- the primary number for ranking -- be certified by a company's owner, CEO or CFO. Responses showed that most companies were happy to cooperate with that stipulation. In a small number of cases, certification was made by an executive at the vice president level but with financial oversight.

In several cases (such as Priceline), sales totals were based on publicly disclosed information because the companies are publicly held or because they publish that information for other reasons.

A number of companies that may have qualified opted not to participate. They include Travelocity, which has not participated for the past few years.

While all cooperating listees did certify sales, it must be kept in mind that even those numbers are difficult to verify because the great majority of travel sellers are privately held and under no obligation to disclose financial data. Also, there is no commonly accepted standard for calculating sales volume, and there is no clearinghouse in the U.S. that tracks non-airline sales, as ARC does for airline sales.

Where possible, Travel Weekly sought to confirm accuracy in the figures by referring to other data and to articles published in the past year. We also reviewed responses for consistency and used whatever resources we had at our disposal to ensure accuracy.

The survey on which these rankings were based included questions involving sales figures; ARC sales; travel-related subsidiaries; percentage of sales from business, leisure, etc.; corporate structure; and others. There were several open-ended questions about recent and planned developments to which companies could reply in any way they felt appropriate for them.

Responses to the questionnaire determined the length of the profiles that accompany each listed agency. Some companies supplied a minimum of information on developments in 2011 or on the company itself; others had a lot more to say. Companies were offered the option of having an executive interviewed by a Travel Weekly editor. Several took advantage of that opportunity.

There might be companies that should be on the list but that escaped our attention. Representatives of such companies should contact Managing Editor Rebecca Tobin at rtobin@travelweekly.com so we can send them a questionnaire for next year's issue.

Corrections:

An incorrect figure appeared for Omega World Travel's sales volume for subsidiaries in 2011. The correct amount was $385 million.

Also, Helix was left off the list of Top Consortia/Cooperatives, ranked by number of locations. Helix had 247 locations in 2011, placing it eighth on the list, following Hickory Global Partners.